1. Field of the Invention
The present invention relates to a laser generator comprising a resonant cavity filled with a laser gas and electric pumping electrodes for causing a laser discharge in the gas of the cavity then subjected to a temperature rise.
Such a generator is used for example in medical or military fields.
2. Description of the Prior Art
Generators of this type have a major drawback which limits their lifespan, namely the degradation of the gas.
Degradation of the gas, generally CO.sub.2, results in the following chemical reactions, caused directly by the high voltage discharge: EQU CO.sub.2 .fwdarw.CO+O EQU CO.fwdarw.C+O
Such degradation of the gas may be prevented by using solid catalysts disposed in the cavity, which promote the reverse chemical reactions. EQU C+O.fwdarw.CO EQU CO+O.fwdarw.CO.sub.2
But the solid catalysts known up to present, such for example as hopcalite, are powdery; despite very stringent precautions during use, they therefore pollute the laser.
Degradation of the gas may further be prevented by adopting an active cathode, having a certain catalytic and oxidizing power, formed form an appropriate mixture of metals and oxides, such for example as copper, nickel, cobalt. Although such an electrode effectively prevents degradation of the gas, it causes on the other hand appreciable pollution of the resonant cavity by deposition of metals and oxides on its internal wall, thus causing another form of degradation of the laser.
Finally, and even with known solid catalysts or an active electrode, the lifespan of the generator and its correct operation remain limited.
The applicant has then tackled this problem of degradation of the laser gas and pollution of the cavity.
As catalysis means perfectly appropriate for the reaction EQU CO.fwdarw.CO.sub.2
the product known under the name of hopcalite is already known. It is a mixture of manganese dioxide and copper oxide. The manganese dioxide oxide plays an oxidizing role and the copper oxide a catalysis role.
In order to ensure the catalytic action, this material must have a particular structure, in the case in point a sponge structure.
Hopcalite is a friable material generator of dust prejudicial to the correct operation of the laser.
In any case, agglomerated grains of hopcalite bonded to a support, inside the laser cavity, do not produce any catalysis effect.
As for the solution of disposing grains of hopcalite inside a filter, it has the drawback that the filter forms, for the gases, an obstacle difficult to cross.
There further exist molecular cells with microporous structure, known under the name of zeolites. These are natural or artificial alumino-silicates. They have been used up to present as vacuum agents, because of their characteristic of retaining in their micropores very large amounts of gas and more especially heavy gases, such as precisely, carbon dioxide gas CO.sub.2.
After studying the reasons for this quality of zeolites, the applicant had the idea of using them in laser generators as supports for catalysts of the hopcalite type, despite the fact that their gas retention property has been up to now considered a disadvantage for lasers.
The document EP-A-No. 0 081 081 teaches, for a laser generator, to dispose a catalyst supporting layer in a chamber separated from the laser cavity itself. But this supporting layer extends relatively far from the laser cavity, so that it is necessary to provide means for heating the catalyst, which is a disadvantage.